1. Field of the Invention
The present invention relates to a heat transfer apparatus for circulating a liquid heat transfer medium by a heat function. The present invention transfers heat to cool various equipments, and provides a cooling apparatus which can control temperature.
2. Description of the Related Art
The details of the related art can be seen in the following U.S. Patents:
(1) U.S. Pat. No. 4,818,845 PA1 (2) U.S. Pat. No. 4,959,526 PA1 (3) U.S. Pat. No. 5,006,689
In a heat transfer apparatus for cooling, heating, and air conditioning, heat transfer utilizing natural circulation has been widely used. However, in actual use, such systems have not been effective in situations other than where heat density and transfer density requirements are low.
There is a heatpipe shown in FIG. 14 as a heat transfer apparatus by use of the heat function having high heating density, which has been recently studied and developed.
In this apparatus, a heating medium 100 is enclosed in an enclosing pipe line 101. If the heating medium 100 evaporates in a heat receiving section 102 of the heat carrier heating medium and changes to gas, and flows into a radiating section 103, gas condenses and liquefies, and returns to the receiving section 102 again by the gravitational effect. This circulation force is a system using gravity. In this system, as shown in FIG. 14, the radiating section 103 is arranged at the section which is higher than the position of the heat receiving section 102, and the arrangement in the course of the pipe line is limited so that flow using gravity can be maintained.
In a system using no gravity, since the circulation depends on a delicate force, which is based on "wetting action (a kind of a capillary phenomenon" of a maintaining material, which is called "wick", circulation force of the heating medium is restricted. Therefore, the heatpipe has been used only limitedly, and a pump is generally used for the circulation of the heating medium. However, the forced circulation apparatus such as a pump is large-scale and the structure is complicated. For this reason, there has been greatly desired a heating medium circulation system wherein a movable section such as a pump and the like is not attached, the structure is simple, reliance is high, manufacturing cost is low, and the condition of use is not limited.
Particularly, in recent years, power semiconductor elements and a power control system using such elements have been frequently used in the semiconductor as used in, for example, an inverter air-conditioner, and the like as a semiconductor electric circuits is miniaturized and its high density is improved. For this reason, it can be considered that a semiconductor control circuit having high heating density will be increasingly used.
Conventionally, in order to cool the circuit elements and substrates, natural draft or forced draft, i.e., fan cooling is generally used. Moreover, the above-mentioned heatpipe or a water cooling type cooling apparatus is used as heating density of a heating source is increased. However, since such a heatpipe has the above-mentioned limitation and the water cooling type needs a water circulation apparatus such as a separate pump, this type is applied to only the large-scale apparatus.
As mentioned above, the cooling apparatus as an example of the heat transfer apparatus is applied to only the apparatus having a low heat transfer density in the heatpipe using natural circulation and no gravity. On the other hand, regarding the heatpipe using gravity, the arrangements (positions) of the structural parts (heat receiving section, radiating section, and the like) are limited. Moreover, there has been a disadvantage in that the apparatus using the forced circulation apparatus such as a pump became large-scale itself.